| Title | Unique features of the Cenozoic igneous rocks of Greece |
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| Author | Pe-Piper, G; Piper, D J W |
| Source | Postcollisional tectonics and magmatism in the Mediterranean region and Asia; by Dilek, Y (ed.); Pavlides, S (ed.); Geological Society of America, Special Paper 409, 2006 p. 259-282, https://doi.org/10.1130/2006.2409(14) |
| Image |  |
| Year | 2006 |
| Alt Series | Earth Sciences Sector, Contribution Series 20060576 |
| Publisher | Geological Society of America |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Greece |
| Lat/Long WENS | 19.0000 28.0000 42.0000 34.0000 |
| Subjects | general geology; structural geology; tectonics; igneous and metamorphic petrology; igneous rocks; geodynamics; paleomagnetism; partial melting; earth thermal history; lithosphere; crustal evolution;
magmas; fractional crystallization; faults, strike-slip; orogenesis; plutons; Cenozoic |
| Illustrations | location maps; geochemical plots; cross-sections, structural; graphs; geological sketch maps; photographs |
| Program | NSERC Natural Sciences and Engineering Research Council of
Canada |
| Released | 2006 01 01 |
| Abstract | The relationship between Cenozoic igneous rocks and the geodynamic evolution of the Aegean region is synthesized. A simplified palinspastic reconstruction of the region is attempted for the last 50
m.y., on the basis of published syntheses of paleomagnetic
data and estimates of amounts of extension and of shortening in nappes. Variability in magma genesis results from hydrous melting of the asthenospheric mantle wedge during subduction,
thermal melting of enriched subcontinental lithospheric mantle as a result of rising asthenosphere, and decompression melting of rising asthenosphere. Break-off of a subducting slab or lithospheric delamination occurred
several times during the
earlier Cenozoic as a result of Late Cretaceous and Paleogene closure of several Neo-Tethyan Ocean basins, triggering the rise of hot asthenosphere. Magmas underwent assimilation and fractional crystallization during passage through subcontinental
lithosphere and crust; these processes were less effective where strike-slip faults provided efficient pathways for magma rise. Available data on the trace elements and radiogenic isotopes are used to identify the magmatic affinities of Cenozoic
igneous rocks.
Unusual features of the Cenozoic igneous activity of the Aegean region are the wide range of rock types in "back-arc" settings and the exposure of both upper-crustal and middle-crustal rocks. This is a consequence of (1) the
numerous microcontinental blocks within the Aegean area, separated by Neo-Tethyan Ocean strands that were destroyed by subduction; (2) orogen-parallel strike-slip faulting resulting from the progressive collision of Arabia with Anatolia; and (3) the
extensional collapse and roll-back of the Hellenic subduction zone over subducting oceanic crust. Magmatism directly related to hydrous melting of subarc asthenosphere lay south of the present
south Aegean arc in the Paleogene; it influenced the
Cyclades plutons in the Miocene and then moved southward again as a result of extension and roll-back to its present position. Calc-alkaline volcanism in Rhodope may be related to the subduction of the
Intra-Pontide Ocean. Lithospheric
delamination or slab break-off produced thermal melting of the subcontinental lithospheric mantle inhomogeneously enriched by earlier subduction, resulting in voluminous shoshonitic volcanism in the Miocene of the northeast Aegean
and the
Oligocene of Rhodope. In both cases, shoshonitic volcanism was followed by minor alkaline magmatism related to the decompression melting of upwelling asthenosphere. The thermal effects of upwelling asthenosphere, coupled with increased
geothermal
gradient from extension, also contributed to the thermal melting of subcontinental lithospheric mantle. The plutonic rocks of the Cyclades and northern Greece resulted from crustal melting by magmas largely derived from the melting of lithospheric
mantle. |
| GEOSCAN ID | 223330 |
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